Have you tried a lot of different brands and models of long-neck sopranos and travel concerts? Can you name some of your favorites?
I have owned 4 long neck sopranos, and one tenor neck. I have only owned one concert with a thin body. It was not named as a travel concert, but its body dimensions were very much like the Kala travel series of ukes.
I also have two Kala travel ukes, a soprano and a tenor.
I really like the Kala solid top spruce long neck soprano, but the Anuenue long neck I gave to my daughter is the nicest one I have owned. It’s all laminate, but lightly built and very sweet and resonant.
The one thin body concert I had was a pacific, and it sounded very nice. A different quality of sound than the longneck soprano ukes I have tried. I gave that and my tenor neck soprano to a very good friend who teaches music.
The tenor neck soprano was great to play, loud, and had a very pretty sound with Martin fluorocarbon strings. It was a Kailua, and I couldn’t really find any information about the brand. There is a company using that name again, but appears that it might be a different company. I didn’t see them showing a tenor neck soprano either.
Ohana still makes one, and I think a higher quality brand may also. 17 frets to the body is wonderful!
I’m very happy with my two Kala travel ukes. They are loud and sound good, comfortable to hold and play. The soprano only gives you 12 frets total.
Based on my experience, if I wanted a concert scale instrument I would get a Kala travel concert. If I wanted a soprano body with a long scale, I would get that Ohana with the tenor neck. But I would be totally happy with a long neck soprano if the tenor neck was too long for me.
Also keep in mind that strings can make a huge difference in sound and playability, along with how you tune them.
Again, for me the main choice is if I want a soprano like sound, get a long neck. If I want a more concert like sound in a compact format, try a travel concert.
Hope that helps!